[mage lang=”en|es|fr|en” source=”flickr”]how telomerase works[/mage]
Genetics Telomerase Question?
A number of scientists who study ways to treat cancer have become interested in telomerase. Why would they be interested in telomerase? How might cancer-drug therapies that target telomerase work?
In both cancer cells, about 70% of all cancer types, as well as in embryo development — telomerase is widely expressed. These are rapidly developing and growing cells and, as such, it is important that the cells reproduce exact copies of themselves. The enzyme telomerase assures that the telomeres (DNA sequences) at the ends of the chromosomes remain the proper lengths. Telomerase in developing embryos is necessary up until the embryo starts turning into a fetus and cells are differentiating and becoming more specialized. At that time, the amount of telomerase falls off with the rate of cellular differentiation and specialization. As the embyo matures, the amount of telomerase falls off until it is no longer seen in the mature somatic cell. Not so in cancer cells, however. Cancer cells are a special case. Cancer cells evolve directly along opposite pathways to that of the developing embryo. Cancer cells start off as normal somatic cells that are mature (fully differentiated and little or no telomerase presence) and have their genes for telomerase turned off. Some where during the course cancerogenesis, the gene or genes for telomerase gets turned back on and synthesizing the enzyme. The telomerase in cancer cells keeps the telomeres at the end of the chromsomes long; thus, the cancer cell “thinks” that it is a young and immature cell that hasn’t undergone differentiation — it becomes immortal as a result of the gene expression for the enzyme telomerase, among other related factors.
How can the expression of the telomerase be used as a marker for cancer cells? The expression of telomerase gene(s) may lead to the formation of cell surface molecular markers for that particular gene or set of genes. It is these cell surface markers that can be used to “prime” the host immune system (immuno-therapy) to react to the presence of these molecular markers on the surface of cancer cells.
Carol Greider, Ph.D., Q&A Part 6